Conventional clock and data recovery systems use a phase locked loop circuit to extract a clock and/or data signal from a serial data stream. The serial data stream may be derived from a number of sources. One such source is a recordable medium, such as a compact disc (CD) or digital video disk (DVD). However, such sources may be subject to periods of data drop out due to issues such as scratches in the disk. During such periods of data loss, conventional data recovery circuits can loose the acquisition of the clock signal, which, depending on the length of the data drop out, may not be recoverable.
It would be desirable to implement a clock and data recovery circuit that is less prone to problems associated with retaining a lock during a data drop out condition.